The present invention relates generally to the field of sealing leaks within pneumatic tires, and more particularly, is directed to a method of automatically sealing such leaks. The method of the present invention includes the steps of introducing an emulsion of butyl latex combined with natural fibers into the interior space defined by a tire, then inflating the tire and rotating the tire to cause portions of the emulsion to flow into and seal the openings.
During the manufacturing process, most pneumatic tires are formed in either a clam shell type of mold or a radially opening and closing type mold. In all cases, the tires are molded under conditions of extremely high pressures and extremely high temperatures. It has been found that the intense heat required in the molding process frequently causes microscopic pin holes to form in the tire during the molding process. These pin holes cause the tire to slowly lose air, thereby resulting in lower than normal air pressures within the tire after passage of a period of time.
When the usual tire with the formed pin holes is in use, air from within the interior space seeps through the microscopic holes due to the internal air pressure. If any of the holes communicate with the tire exterior, the air within the tire can reach the outside to thereby cause the tire to deflate slowly. If the air passing into the microscopic holes does not find microscopic channels to reach the outside, the internal air will progress within the body of the tire itself to the full extent permitted by the configuration and length of the microscopic holes or channels. On occasion, this movement of internal air under pressure can cause belt shifting and actual ply separation.
Prior workers in the art have developed numerous compositions for introduction into the interior space defined within tires for tire sealing purposes. For example, U.S. Pat. No. 3,449,155 describes the use of an aqueous solution of a boric acid salt and an aliphatic acid or salt thereof including glycolic acid. U.S. Pat. No. 3,352,696 illustrates the use of an aqueous composition of polyhydric alcohol, asbestos fibers, gum arabic and gum karaya together with a viscous cellulose ether and an alum compound. In U.S. Pat. No. 1,633,500, an aqueous solution of dextrine is utilized for sealing purposes. Other prior workers in the art have employed ground linseed meal (U.S. Pat. No. 2,347,925), a gelantinized starch suspension (U.S. Pat. No. 2,286,963) and an aqueous mixture of an agglutinant such as acetate and fillers (U.S. Pat. No. 2,074,926).
Experience has shown that the compositions and materials utilized by the prior workers have on many occasions proved defective in that the sealing materials applied frequently would "ball" when in use and would thus not perform the desired sealing function. Additionally, other compositions employed relatively large size fibers of such dimensions that orifice clogging could occur to thereby interfere with the pressurized air filling capabilities of the tire. Despite the interest of the prior workers in this particular field to develop a fully acceptable sealing product, the need remains for a reliable, automatic sealer and method for closing porosity leaks and other leaks in pneumatic tires.